Routine tree deaths doubled
Small background rates of everyday tree death have doubled in old-growth, western forests since 1955, possibly because of climate change, researchers report (SN: 2/14/09, p. 8). In 76 plots with no wildfires or massive pest outbreaks in the western United States and Canada, annual tree mortality crept up to 1 or 2 percent by 2007, says Phillip J. van Mantgem of the U.S. Geological Survey’s Western Ecological Research Center field station in Arcata, Calif. Deaths accelerated in trees of various ages, altitudes and shade preferences, even in national parks — where the air is relatively unpolluted. To explain such widespread effects, van Mantgem and colleagues point to the many consequences of the West’s recent temperature increase. Because more trees now die than sprout each year in the study areas, the forests may be faltering in their role as climate-friendly storehouses of carbon.
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Animal studies link bisphenol A, which can leach from polycarbonate plastics (above), with heart arrhythmias and permanent damage to a gene important for reproduction (SN: 7/18/09, p. 5). And Canadian government studies show that some foodware products labeled as BPA-free contain detectable amounts (SN Online: 7/30/09).
Two decades after the Exxon Valdez oil spill, research confirms that oil still taints Alaskan beaches and that many species have yet to recover (SN Online: 3/23/09).
Some half of North American bird species are wintering in more northerly climes — evidence, some scientists say, of global warming’s biological impacts (SN Online: 2/10/09). Another study blames climate change for the recent failure of birds in the Netherlands to nest twice per season (SN Online: 2/24/09).
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Rot and release
Decomposition of dead trees following hurricanes and tropical storms returns more than 90 million metric tons of carbon dioxide to the atmosphere annually (SN Online: 4/27/09).
Not so green
Substituting plant-based biofuels for fossil fuels will not diminish global greenhouse gas emissions if those biofuels are grown at the expense of tropical forests, a study finds (SN: 3/14/09, p. 17).
From Russia with sootForest fires and agricultural burning in Asia, not industrial pollutants, may cause the plumes of Arctic haze that often waft over northern Alaska and the Arctic Ocean in spring (SN: 3/14/09, p. 13).
Growing bald spot
The world-renowned ice cap atop Mount Kilimanjaro could disappear by 2022, new research suggests (SN: 12/5/09, p. 11).
A boy’s exposure to phthalates in the womb can subtly demasculinize his play during childhood (SN: 12/19/09, p. 10). And a study links prenatal exposure to bisphenol A with subtle, gender-specific alterations in behavior among 2-year-olds (SN: 11/7/09, p. 12).
Nitrous oxide pollution — largely from deforestation, animal wastes and the decomposition of plant material — has become one of the leading threats to Earth’s protective stratospheric ozone layer (SN Online: 8/27/09).
Emissions trump efficiency
The rapid growth of China’s export-driven economy earlier this decade fueled a dramatic increase in carbon dioxide emissions that overwhelmed the country’s substantial improvements in energy efficiency (SN Online: 3/6/09).
Clearing the air
A decline in European aerosols, including fog and haze, over the past three decades has cleared the air but has also fueled 10 to 20 percent of the continent’s warming over the same interval (SN: 2/14/09, p. 9).
Clouded climate picture
A new simulation considers chemical interactions between atmospheric aerosols — the suspended particles that can contribute to haze over some cities (Los Angeles shown) — and various gases. The model gives scientists and policy makers better estimates of the climate-altering effects of greenhouse gases, scientists report (SN: 11/21/09, p. 5).
Leaden IQs and hearts
School-age lead exposure can harm IQ more than earlier exposures — and diminish brain volume (SN: 6/6/09, p. 13). High blood lead levels point to elderly women at greater risk of premature death from coronary heart disease (SN Online: 4/6/09).
The chemical building blocks of foamed polystyrene have been found in the ocean, and laboratory experiments show that the foam degrades into small bits (SN: 9/12/09, p. 9).
Exhausted at sea Emissions from ocean-going ships substantially boost acid rain on shore and may account for more than a quarter of ground-level ozone in some coastal areas, a study reveals (SN Online: 3/27/09).
Certain metal nanoparticles can indirectly damage DNA, essentially by provoking nearby tissue to relay a toxic message to vulnerable bystander cells (SN Online: 11/5/09).
Drinking water may expose people to a persistent chemical used in nonstick products at levels approaching those triggering adverse effects in lab animals (SN Online: 5/12/09.